Production of butadiene



Och 9, 1945. A. E.1 RH 2,386,325

' PRODUCTION OF BUTADIENE `@riginal Filed AprilA 16, 1943 v CONE/VSER CONDE/V567? ATTORNEYS ing material may be soaked in a solution of am-D monium phosphate. The excess liquid may be drained away and the wetted support may then be dried. Alternatively, a solution of ammonium phospho. may be added to the supporting material and the mass may bel dried while it is stirred to maintain uniformity. Whatever pro# cedure is adopted, the supporting material carrying the ammonium phosphate" may be formed into pellets in accordance with the usual method. The pellets may be of any desired size adapted to an'ord maximum surface contact with the neces- I mum contact with the reactant gases.

As the result of dehydrationof the l1,3-butylene glycol, butadiene is produced admixed with unreacted partially reacted glycol.l By passing the vapors through 'a suitable condenser at about 100 C., the unreacted glycol .can be liqueed, separated and returned for further. treatment. The partially reactedl glycol or butenol with water and the butadiene pass the condenser. y The butadiene is withdrawn andpreferably is compressed and condensed by cooling to a liquid although it may be withdrawn and stored in the form of vapor. resulting from the reaction are condensed to liquid which separates into two layers, one oily, conaccesos 24. The condensate is delivered to a collector 2l having a sight glass. whereby the level of the liquid therein may be observed. Butadiene escapes through a pipe 21, is preferably compressed by a compressor 2l. and is delivered to a condenser 29. Cooling water may be introduced through a'pipe 30 and withdrawn through a pipe 3l The butadiene in the lliquid phase may be withdrawn through a. pipe 32 and delivered to any suitable storage receptacle.

The liquid from'the collector 25 is delivered through a pipe 33 controlled by' a valve 14 to a separator 35 having a sight glass 36 ypermitting observation of the liquid levels.. The liquid separates into two layers. The 'upper oily layer, containing part ofthe butenol, may be withdrawn through a pipe 31 and delivered by a pump 38 and pipe 39 to the pipe I0, where it mingles with the glycol introduced to the vaporizer il.

.The liquid in the bottom of the separator 35 isv withdrawn through a pipe 40 controlled by a valve 4I and is delivered by a pump 42 and pipe 43 to a rectiiler 44 having the usual plates or trays 45. The bottom of the rectier' is supplied The partially reacted-glycol and' water f taining part of the butenol, and the other watery. A

which also contains butenol. The oily layer can heV withdrawn and returned for further treatment. The watery layer is delivered vtoa fractionating column. An azeotrope of butenol and water is withdrawn at the top of the column and returned for further treatment with the catalyst. Water is withdrawn at the bottom of the column.

The procedure will be readily understood by Vreference to the drawing. it being understood that the apparatus described is merely illustrative of- `suitable equipment for the purpose. The reactor 5 maybe a tubular chamber of suitable material surrounded by a heating jacket 6 to which theheating iluid is introduced through apipe l and withdrawn through a pipe 8. The catalyst 5 is disposed within the chamber 5 in the form of pellets of suitable `size to effect the desired resuit.

1,3-butylene glycol is supplied through a pipe I il to a vaporizer H which may be heated, 'for example; by passage of a suitable liquid such as Dowtherm through a jacket 2. The heating liquid is introduced through a. pipe I3 and with-l drawnV through a pipe i4. Theglycol is thus vapgrized and delivered to the chamber 5 by a pipe 'I'he gaseous products of the reaction are with-` drawn through a pipe I8 and delivered to a condenser l'lv supplied with cooling liquid such as water -through a pipe i8. The water` vescapes through a pipe I9. The condensate, consisting of unreacted glycol, is delivered by'a pipe 20 to the pipe I0 and vaporizer I l .'I'her'emaining vapors are delivered by a pipe 2l to a condenser 22 through which a cooling liquid suchas water is circulated'by pipes 23 and with heat by means of a coil I8 through which any suitable heating medium may circulate. The rectification results in the separation of water at the bottom which may be withdrawn through the `pipe 41 controlled by a valve 48. The azeotrope of 'partially reacted glycol or butenol and water escapes through a pipe 45 at the top of the rectifier and: is delivered to a condenser l0. Cooling water may be introduced through the pipe 5l and withdrawn through a pipe 52. The

condensed azeotrope is delivered through .a pipe 53, pump 54 and pipe 55 to the pipe I0, and is thus returned for further reaction in contact with the catalyst.

'I'he practical operation of the invention will*v be readily understood from the following examples: l

, Example I A catalyst was prepared by soaking 4-8 mesh Celite V in a saturated aqueous solution of diammonium phosphate. The mass was 'drained a'nddried at 100 C. It was placed in the reactor and heated to a temperature of 30D-320 C. A

aqueous solution of 1,3-butylene glycol was vaporized and passed through the catalyst.. 'I'he butadiene was separated as hereinbefore dev scribed. After 80 days of operation, thecatalyst had disintegrated only to the extent of about 15%. Satisfactory yields of butadiene were obtained. l A Eax'mzplev II In an operation similar minst described m Example I. I employed a catalyst composed of about 15% dlammonium phosphate mounted on feldspar-bonded silica of approximately 4-8 mesh size. aqueous 1,3-butylene glycol solution was vaporized and delivered to thecatalyst mass at a rate of 25-35 grams per hour. After 56 days of operation, the catalyst showed only about 50% disintegration. isfactory.

The foregoing examples are merely illustra.-`

tive of various modifications which can be made in the operation of the invention. Two elements are, however, important, the use of ammonium Phosphate as the active catalytic material and the use of a support vconsisting essentially of silica. The use of these elements of the invention ensures satisfactory yields. and continued catalytic activity over long periods of time.- The Yields were satsowas ing the advantages thereof.

This application is a. division of my uoso-pending application Serial No. 483,343 filed April 16, 1943.

I claim:

s s3 The method ofaehydrmng Lex-butyl@ glycol to produce-1,3-butadiene which-comprisespassing the zlycol in the vapor phase over a catalyst body 'consisting oi ammonium phosphate on an inertsupport composed essentially of silica in the formfoi ieldspar-bonded silica.

ARTHUR nLoRcH. a 

